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3 to 4 speed speedo gears?

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53w View Drop Down
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Post Options Post Options   Thanks (0) Thanks(0)   Quote 53w Quote  Post ReplyReply Direct Link To This Post Topic: 3 to 4 speed speedo gears?
    Posted: May/06/2016 at 5:18pm
I changed from an 3speed manual to a 4speed manual.

Will the 3 speed speedo gear work in my four speed?

If not, where do I buy the correct one and how do I figure which one I need for different rear end ratios

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Post Options Post Options   Thanks (0) Thanks(0)   Quote tyrodtom Quote  Post ReplyReply Direct Link To This Post Posted: May/06/2016 at 5:23pm
Nobody can hardly say without knowing what 3speed you had, and what 4 speed you switched to.
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53w View Drop Down
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Post Options Post Options   Thanks (0) Thanks(0)   Quote 53w Quote  Post ReplyReply Direct Link To This Post Posted: May/06/2016 at 6:12pm
very good point, but I not too sure myself

1974 javelin 304 with 3 speed manual on the floor factory

changed out to amc t10 4 speed manual out of ?.... , not sure was told it was amc t-10 and it would fit my javelin and it did.

wish I had exact numbers, but that all I know.

Can I take the speedo cable and gear from 3 speed manual that is hanging there and put it in the 4speed and have it work?

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1970390amx View Drop Down
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Post Options Post Options   Thanks (0) Thanks(0)   Quote 1970390amx Quote  Post ReplyReply Direct Link To This Post Posted: May/06/2016 at 9:30pm
probably, the only question would be the tooth count on the output shaft of each transmission. Should work how accurate is another question.
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53w View Drop Down
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Post Options Post Options   Thanks (0) Thanks(0)   Quote 53w Quote  Post ReplyReply Direct Link To This Post Posted: May/06/2016 at 10:19pm
Originally posted by 1970390amx 1970390amx wrote:

probably, the only question would be the tooth count on the output shaft of each transmission. Should work how accurate is another question.


That's what I need to know. It looked like it would fit in the hole, but was unsure if gear was correct to mesh with the trans gear.

I didn't want to put it in with out asking first if it was right fit to match up with 4speed trans gear.

I don't mind mph being off due to tooth count, I can fix that later with correct gear. I maybe swapping rear ends out any way and ratio may change, thus gear tooth count will change again.

I just trying to get speedo to move and make sure everything works.

so does anyone no 100% that the gears will all mesh, taking 3speed speedo cable and gear out of 3 speed and putting it in to 4speed?
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Post Options Post Options   Thanks (0) Thanks(0)   Quote rocklandrambler Quote  Post ReplyReply Direct Link To This Post Posted: May/07/2016 at 1:12am
Your TSM should list all the transmission gears on the last page of the TRANSMISSION section.
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Post Options Post Options   Thanks (0) Thanks(0)   Quote vinny Quote  Post ReplyReply Direct Link To This Post Posted: May/07/2016 at 6:13am
Why not get a flashlight and look in the holes to see if there are obvious differences? 

It probably doesn't mean anything to most of you fellows but by going from a 3.73 to a 3.07 differential in my truck it now seems to read correct in kilometers per hour by just doubling the number.
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Post Options Post Options   Thanks (0) Thanks(0)   Quote sidewinder Quote  Post ReplyReply Direct Link To This Post Posted: May/07/2016 at 7:29am
If you need a new gear I believe AMARK offers several....

Chuck Page  
Chuck Page ,AKA Sidewinder
1968 "BLACK CHERRY" Javelin
Previous owner of 2013 Heritage Cup winner 1970 BBO AMX


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Post Options Post Options   Thanks (0) Thanks(0)   Quote 53w Quote  Post ReplyReply Direct Link To This Post Posted: Jun/11/2016 at 12:59am
I worked on it today and the 3speed speedo gear and cable end did fit into the 4speed. The Speedo seems right on with GPS read out.
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